Field of the Invention
The invention relates to gas turbine engine composite airfoils and, particularly, for metallic attachments for composite airfoils for mounting in aircraft gas turbine engines.
Description of Related Art
Bypass gas turbine engines of the turbofan type generally includes a forward fan and booster compressor, a middle core engine, and an aft low pressure power turbine. A low pressure turbine rotatably drives the fan and booster compressor via a low pressure shaft, all of which form the low pressure rotor. Composite airfoils have been developed for and used in blades for rotatable stages of the booster compressor and in stator vanes disposed between and upstream and downstream of the blades as well in other sections of the engine such as in the fan section (fan outlet guide vanes).
It is known to manufacture aircraft gas turbine engine blade and vane airfoils from composite materials. It is difficult to attach the composite airfoils to a metallic attachment for mounting the blade or vane to a metallic rotor or stator portion of the engine. This is a challenge due to the magnitude of loads and limited size of the components. Typically, the attachments of these composite parts are the challenging part of that implementation. Typically, it is desired to have an integral composite/metallic system that takes advantage of the composite weight reduction and complex machining of a metallic interface. Joining these two systems in the past has been by simple adhesive bonds. These bonds are subject to forces and moments that tend to dislodge the composite airfoils from a metallic mount of the blade or vane.
It is highly desirable to provide mounts for securely and robustly mounting composite airfoils in both gas turbine engine rotor and fan frame assemblies that resist forces and moments that tend to dislodge the composite airfoils from a metallic mount of the blade or vane and that will enhance the life of the airfoils and the fan frame assembly. In a broader sense, it is highly desirable to provide mounts for securely and robustly mounting composite parts that resist forces and moments that tend to dislodge composite elements from metallic mounts on the part.